The invention relates to the make-up of pages for reproduction.
For a variety of kinds of publication, it is desired to reproduce pages which include material of different kinds, for example, picture area, of which the originals are photographs or pieces of original artistic work, together with background tints, borders and text and perhaps logos. For reproduction, a set of color separations of the entire page, usually in cyan, magenta, yellow and black respectively, has to be produced.
In a conventional page make-up process, color separations for each of the picture areas are prepared. Masks providing the borders, tints, and the like, also required are then produced by manual and photographic means. The masks and the picture area separations are next combined by means of a contact frame to obtain the final product, that is, the set of separations for the whole page. The process cannot be performed quickly, the generation of the complete masks being particularly time consuming, with the result that the process as a whole is expensive.
Computerized systems for page make-up have therefore been developed. In the use of these, the first stage comprises the scanning by a graphic arts drum scanner of all the material to be included in the final page apart from contributions to be generated by the operator. The data generated by the scanner is supplied to a computer for recording in digital form in a suitable storage medium for example hard disc. The operator's contribution is made by means of a plotting table, or a cathode ray tube (CRT) monitor with a tablet or digitizer.
Where a plotting table is used, a planning film is exposed at the same time as the original material is scanned. The film obtained is mounted on the table, in a position corresponding to the required position on the completed page of the image it represents. This position is then entered into the computer through a keyboard or by use of a cursor. When all required images have been positioned in this way, the operator then enters into the computer store the additional material, for example, text, tints or borders, required to complete the page. Either when the operator has finished, or in parallel with his work, the computer assembles, pixel by pixel, a new record in its store which represents the final set of separations for the full page.
Where a monitor is used, the operator calls up data from the pre-scanned records and positions it where required on the CRT or display unit. Tints and borders are then introduced by use of a stylus on the tablet or by way of a keyboard. The final result is the same, a record generated pixel by pixel which represents the entire area of the separations for the required page.
Such page make-up systems are very versatile but they are also very complex and therefore expensive.
It is therefore an object of the invention to provide a method and a means for generating masks which permit the separations for page reproduction to be prepared in a simple and economical manner.
It is a further object of the invention to provide circuit arrangements whereby a color scanner and a video graphic system can be employed in the generation of separations for use in page make-up.